Features of low-temperature thermal expansion of n-type Bi2Se3 single crystals in magnetic field

Abstract

Tensometric study of n-type Bi₂Se₃ single crystals in dc magnetic fields to 6 T in a temperature range of 7–23 K detected a weak negative thermal expansion (NTE) in the basal plane. The NTE increases with the field strength and depends on its orientation with respect to the trigonal c axis. In a magnetic field of 6 T, parallel to the c axis, the linear NTE coefficient reaches −7 · 10⁻⁷ K⁻¹, and a minimum sample length is reached at a temperature of 13 K, where a Hall carrier concentration maximum is also detected. The found magnetoelastic anomaly can be associated with the topological insulator state.